Back now from vacation, and while I was away several people sent me links to point out that string theory promoters definitely aren’t taking a vacation. Links here with a few quick comments, followed by something about the issue of making fun of string theorists.
- Lenny Susskind has a quite good new book out about classical mechanics (see here), but the Economist doesn’t want to talk to him about this, instead it’s the usual string theory promotional effort:
These extra dimensions can be arranged and put together in many different patterns, in a variety of different ways. Not billions, trillions or quintillions of ways, but many more than that. The ways these dimensions are put together into these tiny little spaces determine how particles will behave, what particles will exist, what the constants of nature are—quantities like dark energy or the electric charge of an electron. In string theory all those things are features of the ways that these tiny dimensions are put together. The tiny dimensions are like the DNA of the universe.
- Last month Cumrun Vafa was in Bangalore, explaining (see here, slides here) among other things about the significance of the web of string dualities that makes up M-theory:
String dualities [are] in my opinion perhaps the most fundamental discovery that physicists have made in a century.
Note that the past century includes General Relativity (barely), quantum mechanics, gauge theory, the Standard Model, as well as quite a few discoveries in other areas of physics.
- The Strings 2013 conference included the usual public talks promoting string theory. Witten’s was String Theory and the Universe, which was pretty much unchanged (minus optimism about SUSY at the LHC) from similar talks he has been giving for nearly 20 years (since 1995 and the M-theory proposal). Linde’s was Universe or Multiverse?, about the “new scientific paradigm” of Multiverse Mania. He argues that the virtue of this is that it is “impossible to disprove”.
- David Gross’s public talk on The Frontiers of Particle Physics had nothing to do with string theory, focusing on explaining the standard model and some of the questions it leaves unanswered. Much more interesting was his outlook talk at the conference which included the usual exhortations about string theory being alive and healthy, flourishing with many new and brilliant string theorists, but also included some material unusual in such a venue and much more challenging for his audience. His reference to connections between string theory and condensed matter physics described this as having been “overhyped by our community”. About AdS/CFT, he noted that it “does not provide a satisfactory non-perturbative quantum gravity”.
He commented on the lack of connection between the talks and HEP physics, saying that it was “important that string theorists not retreat into quantum gravity”. About SUSY, he characterized it as “still alive, but not kicking”, and he argued that the LHC results of the past year have made more likely the “Extremely pessimistic scenario” of an SM Higgs, no SUSY, no dark matter, no indication of the next energy threshold. Since “HEP is where string theory connects to reality”, he made the point to the audience that “if this scenario materializes we are all going to suffer.”
I’m not sure why he picked this date, but he encouraged those with post-1999 Ph.D.s to realize that it was now quite possible that those who came before them had “somehow got it wrong”. This was the first time I’ve seen an influential member of the string theory community raise this possibility and call for people to consider it seriously.
- Sean Carroll deals here with arguments from the “Popperazi” that the string theory anthropic multiverse is pseudo-science by ignoring the serious arguments being made. He has his own definition of what science is, which looks to me to open far more questions than it answers. About string theory unification itself, the question has never been whether it’s science, but whether it’s an idea worth pursuing given the ways in which it has so far failed. The best argument for continued pursuit of the idea is of course that there aren’t obviously better ones around, but this raises its own issues.
Sabine Hossenfelder has a posting about an introduction to a Lawrence Krauss talk where the joke was made that “String theorists have to sit in the back”. The context for this was a controversy about the place of women at a discussion involving Krauss hosted by an Islamic group. Like Sabine, I don’t want to discuss here that controversy, just agree there’s a good case to be made that it’s no joking matter. I think she makes a mistake by interpreting the joke as an attack on string theorists (it’s a joke, after all, open to many interpretations), but I was struck by her perception of string theorists as an embattled minority under unfair attack, as well as the claim that it’s not all right to in any way make fun of them.
The situation these days is clearly very different than it was back in 2004 when I started this blog, partly because of the past decade of failure of string theory unification to get anywhere, partly because of the negative LHC results, partly because of the multiverse, and partly because of the public behavior of some in the string theory community in reaction to criticism. Given the high profile ongoing promotional campaign exemplified above, I don’t think we’re yet at the point where criticism of string theorists is “kicking them when they’re down”, and humor is sometimes the best way to make a point concisely. Probably the most incisive criticism of string theory ever made was made in a cartoon, and personally I’ve never understood how it is even possible to take arguments like Linde’s seriously (and am not even sure he does…), so I see a role for humor in charting the continuing story of the collapse of the heavily influential string theory unification paradigm.
Update: If you noticed more than the usual sloppiness, incompleteness and incoherence, maybe it was because this got published early, while I was in the middle of writing it.
Update: The latest on the philosophy of science from Linde (see here), who is at a workshop in Bad Honnef this week.
The multiverse is the only known explanation so in a sense it has already been tested
Is it all right to make fun of this, or should one seriously discuss the scientific merits here?
Wired Online magazine has a new ST related story you may want to look at http://www.wired.com/wiredscience/2013/07/hidden-particle-world/
Thank Tim,
That’s a well-written article, but I’m no condensed matter expert, so will leave the question of what fraction of the claims discussed are over-hyped to the experts (and David Gross…).
A few years ago, there were a lot of similar claims being made about string theory and heavy-ion physics, but those seem to have suffered from a pretty high hype level, with the ideas involved not working out very well (this topic disappeared at String 2013, from what I can see).
The post 1999 Ph.D comment was made because of one slide in Jeff Harvey’s talk where he mentions a disconnect between the older and younger generations of string theorists (a year he also admitted to being arbitrary). Harvey’s overview was interesting, he also noted that the AdS/CMT work, although not the panacea some people claimed it might be, was making more concrete progress. I don’t think Gross or Harvey were happy that more people are working on AdS/CMT rather then AdS/QCD, but it really is a matter of where progress can be made as opposed to where they wish it could be made.
1997-98 was when the AdS/CFT breakthrough happened. Gross might choose 1999 as the dividing line if he wishes to club AdS/CFT with (stringy) physics of the generation past.
If, however implausibly, string theorists *were* sent to the back of the bus, it wouldn’t a prejudice, but an a posteriori judgment on their past sins against modesty and civility.
I hope that this change in attitudes will also be translated to other things. In his book “Strange Beauty” George Johnson tells an amazing story about the role of James Bjorken in the recognition of quarks as actual particles, so I thought – here is a guy who actually deserves the Fundamental Physics Prize… Did he fall off people’s radar for some reason, or does he still have a chance?
B.B.,
While Gross is changing a bit his tune in response to experimental results from the LHC, he’s not an FPP winner, and has no vote there. Linde and Witten are, and they haven’t changed their views at all as far as I can tell. The thing which is going to change the FPP choices in the future is the addition of a large number of experimentalists to the group making the choices (due to the LHC special award this year). I have no idea how that will play out.
Unless there’s some news about the FPP, it’s kind of off-topic here (as well as the work of Bjorken nearly a half-century ago), so I encourage commenters to stick to comments related to the posting.
Just read Sabine Hossenfelder’s blog post and all the comments. At least in the comments she makes it clear that she doesn’t approve of string theory hype any more than string theory derogation. It’s the interference in the process of rational assessment she is objecting to. But on this I have to say she is alarmingly late to the party: [irrelevant material about Krauss deleted]. I have to agree with one of the commentators: string theorists are now reaping what they sowed when for so long they promoted their theory on the back of zero experimental support. That was never going to end well, and now we are seeing that. Reaper, whirlwind…
I am confused by Sean Carroll’s statement that the existence of gauge theory is (crude) data that is explained by string theory. Could one not equally well assert that the existence of fermion and bosons are data explained by string theory?
If the existence of gauge theory QFTs is indeed explained by string theory (but string theory has no Wilsonian definition) then should not string theory also explain why and how the Wilsonian ideas work?
I didn’t interpret it as an “attack”, this makes it sound way too aggressive and also way too important. I interpret it as a representation of public opinion, basically. The guy is a semi-popular figure and he was trying to make a joke (funny or not) that he thought would appeal to the audience.
I just don’t think ridicule is going to be conductive to scientific inquiry. I would prefer if both the public as well as young students have a chance to get an objective impression of the situation.
Your blog has added, and still adds, criticism that had been lacking. Of course criticism is always unpleasant for some people which isn’t nice, but then nobody says that science has to be nice. This is fine with me, but criticism is only useful though when it has content and I don’t want stupid jokes to affect people’s opinions. That’s all.
Nasren, I’ve been writing since at least 2006 about the problem that the public opinion affects researcher’s decisions, that this problem is becoming larger due to the increased connectivity of our social networks generally and the scientific community specifically, and that I don’t think this is good. This isn’t a new theme on my blog, if you care to look. But yeah, I’m late to the party, sorry for not having been around to comment on the elan vital.
anonyrat,
Sean’s argument that “string theory explains gauge theory” is, for good reason, not one that string theorists typically use, and I don’t know why he’s using it, especially in the context of trying to explain what the scientific method is.
Bee,
I think we’re in agreement about the importance of having objective arguments on all sides available, and that’s something I’ve tried to provide, in a situation that, way back when, was dominated by a one-sided public relations campaign. More recently, both sides of arguments about string theory have gotten an airing, and I think the joke you reacted to was just motivated by someone noticing that there was a controversy, which is not a bad thing. About the use of ridicule, I think it’s a problem when used to deal with serious arguments, appropriate when used to deal with ridiculous ones. Undoubtedly I make mistakes, but I hope that I mostly get right which is which.
I just saw your posting about Occam’s razor, and one thing that struck me about Sean’s definition of science is that this plays no part in it. It’s true that in some contexts one has to be wary of the principle and it may not be appropriate. But I do think it’s a very fundamental part of the scientific method. One thing it does is tell you about a sort of pseudo-science you have to watch out for, theories that don’t actually explain anything, bad models where you just add complexity to keep them out of trouble with experiment. Linde’s promotion of a new paradigm where you deal with explaining things by saying anything can happen in your theory, (and claim that as a virtue, crossing the line into the ridiculous) is an indication of where you end up if you think Occam’s razor is worthless.
““Extremely pessimistic scenario” of an SM Higgs, no SUSY, no dark matter, no indication of the next energy threshold.”
The above sentence really struck me. Especially the part about ‘no dark matter’. Does this actually mean that dark matter is not real and therefore the composition of the universe is wrong? Or does it mean something else?
Does MOND or TeVeS now more to the front? Or am I reading way to much into those three words?
John,
He was just referring to the (all too real) possibility of no heavy WIMP dark matter particle showing up in the LHC data or the direct detection experiments, a possibility that has always been part of the hope for new physics at the LHC scale, SUSY and other wise. One alternative he mentioned was axions. I’d rather not start a discussion of dark matter alternatives here, that’s a very different topic.
On the ST comment, I too thought it was a silly joke of no significance from a non-physicist looking for a quirky comment.
There is another important lesson here – Chairs should leave humour to the speaker, because you don’t know what might offend your visiting speaker. It would have been an awkward talk if Larry had reacted the way Bee did!
Seen this? Apparently SUSY can’t be seen at LHC but can at ILC. Now I understand …
http://phys.org/news/2013-07-ou-physicists-rationale-next-generation-particle.html
Apologies Bee. I suppose it just seemed to me that a mild joke that was mostly against religious irrationality, not string theory, was a strange thing to protest when there is daily a huge amount of hype emanating from multiple sources. It seemed like a strange point to draw the line.
Bob,
A good candidate for “This Week’s Hype” and further evidence that all university press releases about HEP theory are outrageous hype.
It will be interesting to see if anyone seriously tries to convince the Japanese government to spend the many billions an ILC will cost using this kind of argument.
Peter, sorry for being off topic. Maybe in one of your future posts you can mention this poll: https://sites.google.com/site/fieldsmedal2014poll
I am currently unable to view the talk using the link (very slow loading for some reason), so I have to ask: With such an attitude, what would hinder me to postulate some omnipotent Creator that moves all the particles in the Universe according to his whim, or that he (Linde) is a brain-in-a-vat? I find it difficult to believe that a physicist would make a statement to that effect…
Bob,
Baer has been working on supersymmetric theories which are “natural” in the sense of having a very low mu term down between 100 and 200 GeV. This sets the scale of the Higgsino mass; these fermions are vector-like, uncolored, and extremely difficult to find at LHC. There is signficantly better prospect of finding them at a lepton collider like ILC, particularly given that Baer’s favorite mass range is below the proposed ILC center of mass energy.
Whether that warrants another collider (which is probably going to happen anyways) is a matter of taste, but the science is solid. Peter is right that university press releases are overhyped, but it’s best to get the facts and understand the science before making condescending remarks; sometimes they are warranted, but other times they expose ignorance.
Cheers,
P
but the science is solid
No, it’s disingenuous. Naturalness (at least in the MSSM and simple extensions thereof) does require light Higgsinos, but it also requires light stops and light-ish gluinos, and the LHC is doing a depressingly good job of ruling those out without any help from an ILC. This attempt to refocus on tree-level naturalness and handwave away the loop corrections just doesn’t make sense. In general, a lot of the Snowmass process involves people distorting physics to reach the conclusions they want about the future of the field.
I noticed an upcoming talk entitled “The Standard Model is complete” in the “New directions in Theoretical Physics” part of the linked conference. We’ll have to wait and hear what is said…
T.G.,
Thanks, that’s a topic undoubtedly to come up in the next year.
anonymous,
There may not be much meant by this title other than a reference to the fact that the LHC has discovered the last part of the Standard Model (the Higgs).
anon,
Large regions of soft-breaking parameter space are better constrained by a lepton collider than LHC, period, end of story. If you’re motivated purely by naturalness then yes, the stop mass is the most important quantity, but as you know a theory with a 10 or 50 TeV stop is a heck of a lot more natural than a theory with no cutoff whatsoever.
Bottom line, you’re wrong: it is not disingenuous to discuss how certain experiments might be better for ruling out certain parts of parameter space than others. In fact, it’s required, and it’s science. Baer’s scenario is not my cup of tea, personally, but it’s easier to probe light Higgsinos at ILC. There is no question here.
P
Maybe somebody should sit Andrei Linde down and point out the similarity of his remarks to the pseudo-scientific apologetics for Marxism under the Soviets throughout much of the 20th century. You would think he would have the sense to steer way clear of that crap.
Bottom line, you’re wrong: it is not disingenuous to discuss how certain experiments might be better for ruling out certain parts of parameter space than others.
I agree with your statement, but that’s not what’s happening here. The point is that the only argument for Higgsinos being light enough to be in ILC range is naturalness, and it’s disingenuous to use naturalness as an argument without noting that the LHC is already putting the whole scenario under strain. It’s true that the ILC is a great machine for discovering light Higgsinos, but if you give up on naturalness the Higgsinos could be anywhere from 100 GeV to many TeV, and the ILC covers only a fraction of that range. If all that was happening here is that people were noting that the ILC is better for “certain parts of parameter space”, I would have no problem with it. The trouble is the argument attached to favoring those parts of parameter space.
Hi Peter,
I read with interest Sean Carroll’s blog post ostensibly in defense of multiverse theory as a sound scientific pursuit. After setting up his own three-part proto-definition of ‘science’ which is sorely lacking in many key facets, he goes on to lambast those who have other demarcations. Specifically, three:
1) Science assumes naturalism
2) Science requires falsifiable theories
3) Science requires reproducible experiments
He then makes a rather astounding boast, “…each one of these is straightforwardly false.”
This is where his blog post became very interesting for me. I was intrigued to hear how he might straightforwardly demonstrate the error with these claims.
He didn’t even come close.
In fact, he backed down almost immediately when it came to the falsifiability claim. He said it was a tricky claim and he couldn’t/wouldn’t do it justice let alone straightforwardly demonstrate it to be false. His argument against the falsifiability criterion seems to be something like – well, String theory and Multiverse theory are just different from other non-falsifiable theories because it is “clearly are saying something concrete about the world.” And also because people who are employed as Scientists are studying it so therefore it must be science.
He totally took a copout. As Sean probably well knows, the problem with the landscape is that it isn’t falsifiable *even in principle* and not just because we lack the experimental apparatus to test its claims.
Anyways, he offers much much less than his boast of a straightforward refutation of the falsifiability criterion as a limit on the definition of science. The same goes for his supposed refutation of reproducible experiments. The point is that an experiment must at least be reproducible in principle.
I think the multiverse proponents should learn something from the religious apologists. They could teach them a thing or two. This apologia for multiverse theory is not up to snuff.
Adam, the trouble is that they’re acting like they have apparently learned something from the religious apologists, namely, that such apologetics are acceptable as well socio-politically expedient—this is what you do to defend what you “know” to be the truth. As I mentioned, many Marxists once upon a time routinely indulged in a similar practice; presumably a few still do. (Apologetics for capitalism are more in vogue these days.)
I share your disillusionment with Sean Carroll’s attempt to defend this position. That said, I suppose he has done us all a service by giving it his best shot and coming up so short. That’s one way to realize that such a position simply isn’t defensible.
Bee,
I think the notion that ridicule has no place in scientific debate is extremely naive. Ridicule is appropriate when somebody makes ridiculous claims. If you are offended by the kind of sharp elbows debate that can be seen now, you are really lucky that you weren’t around for the great quaternions vs vectors debate a bit over a century ago – not to mention almost all of the scientific debates before and since.
As Peter has been mostly very politely pointing out for years, string theory has often been eager to make claims it couldn’t back up. These claims influence public opinion, funding, and faculty appointments. When they are false, they deserve to be corrected forcefully.
“Is it all right to make fun of this, or should one seriously discuss the scientific merits here?”
In a setting where the presumed reader has some basic knowledge of science (such as this blog), I’d say it’s perfectly fine to make fun of this statement. However, were I writing to a more general audience, I probably would bother to write 2-3 sentences explaining why this is a ludicrous statement.
You got me to watch Gross’ conference summary. I thought he was a bit more balanced than you portray… he presented the optimistic scenario, did say that entire (which heavily leans on low energy breaking of SUSY) package was alive but not kicking.
I thought, did it ever kick? It was always a sleeping princess waiting for an experimental prince to kiss it and animate a kick.
But as he emphasized, there is a continuum all the way to the extreme pessimistic scenario. The data will decide, but he nicely emphasized that creativity in suggesting new experiments is called for. Of course, some of the best experimentalists, from Luis Alvarez to Mel Schwartz to Burt Richter have been saying that for 30 years at least.
Goletabeach,
It is not that Peter portrayed Gross’ speech in an unbalanced way. The way I see it, Gross said there might be a door to non-string theory that Peter has been advocating these many years, and Gross has finally admitted it’s possible existence. And this speech occurred in “Strings 2013”. That is a sign of a change.
Jim Akerlund
Though true, I do find a slight bit of irony in how “completeness” could be listed in the “new directions” section. The ambiguity of the title makes it all the more enticing. There are plenty of other post-Higgs talks in the same conference that presumably cover that material.
“About the use of ridicule, I think it’s a problem when used to deal with serious arguments, appropriate when used to deal with ridiculous ones.”
The problem is that you usually don’t consider any serious arguments on this blog. You find the most ridiculous press releases and act like they describe everyone in string theory. There are good reasons for taking string theory seriously as a theory of everything, and even if it’s not a theory of everything, it has proven to be a useful framework for solving lots of other problems. You do your best to ignore this fact on your blog, but it’s the main problem with your thesis. It just doesn’t make sense to put down an entire field when it has proven successful in so many ways.
Bob Jones,
In my book and here, I think I address seriously serious arguments for string theory (as well as ridiculing some of the ridiculous ones). I’d be curious to hear of any serious press releases about progress in string theory that I’ve ignored.
One of the main problems with string theory is that the leadership of the field has pretty much uniformly refused to engage seriously with the issue of the very real and dramatic failures of the string theory unification program, preferring to keep repeating the same hype, trying to pretend they don’t have a problem. As long as this goes on, others should point this out.
Peter, interested n your views in yet another LHC related meeting at KITP
http://online.kitp.ucsb.edu/online/lhc-c13/
“successful in so many ways” Is this a joke ?
Shantanu,
Thanks. I did get a chance to look at the Lykken summary talk, which seemed to be quite good.
Thomas,
You wouldn’t know it from reading this blog, but yes, string theory has been successful in many ways.
It doesn’t matter whether string theory is a correct fundamental theory because string theory has some general features that are expected to hold in any successful theory of quantum gravity. For example, string theory provides several concrete realizations of the holographic principle. It has taught us conceptually how black hole entropy can be accounted for by microscopic degrees of freedom in a theory of quantum gravity. These results are interesting because they depend only on the general features of string theory, not the specific details.
But even if string theory had nothing to do with gravity, it would still be interesting because of its connections to quantum field theory. For example, string theory has shed light on the mathematical properties of scattering amplitudes in gauge theories. It provides a tool for studying strongly coupled quantum field theories, and there are now probably hundreds of papers which use string theory methods to understand aspects of nuclear and condensed matter physics. More generally, string theory predicts a web of relationships between different quantum field theories, and by understanding these relationships, physicists have developed new ways of computing quantities of physical interest. Again, these results are all true and interesting regardless of whether string theory provides a correct theory of everything.
Finally, even if string theory had nothing to do with physics, it would still be important because of its applications in pure mathematics. The dualities discovered by string theorists imply profound relationships between seemingly different mathematical structures. It was string theorists who first discovered mirror symmetry, a powerful new tool in enumerative algebraic geometry. Methods from string theory were used in Borcherds’ proof of the monstrous moonshine conjecture, and string theory has inspired new mathematical ideas, like the notion of a stability structures on triangulated categories.
Well, that discussion has already happened at
Farewell To Reality – Comment Section
… Bob Jones vs. The Rest.
“You wouldn’t know it from reading this blog, but yes, string theory has been successful in many ways.”
One interesting thing to do when reading, especially stuff in politics, is turn the sentence around so that it says the opposite, and see if it makes more sense that way. So in this case, “If you read this blog, you will see that string theory is a failure” is actually more true than the original sentence.
“It doesn’t matter whether string theory is a correct fundamental theory because…..”
In this case, you can supply any word after the “because” but it won’t change the meaning of the sentence, which is also cool.
So DrDave, applying your principle, that means that the new sentence is actually less true than the original?
Dr. Dave,
Very clever! Your silly argument kept you from dealing having to deal with Bob Jones’ point.
I’ll give you the benefit of the doubt, though, and assume you have good reasons for your strong statements. Please, explain to us how string insights into AdS/CFT, mirror symmetry, or QFT dualities have been a failure.
All,
Please, unless someone has something interesting to say about the actual topics in the posting, enough. The only thing in the posting about string dualities was Vafa’s claim that they’re the most fundamental discovery in physics of the past century, I suppose those who want to claim them as the main success of string theory could address the question of whether they agree with Vafa.
In flagrant violation of your request that comments be on-topic, may I point out that labelling your links ‘here’ makes them a little more difficult to grab with a keyboard-driven browser or assistive technologies? It’s a minor nit but I’ve been meaning to mention it for a while.
Otherwise, the multiverse is an answer to a philosophical objection, I don’t even think it was supposed to describe any physical effect. It’s neither science, nor useful.